Fuel injection pump



July 2, 1957 H. HOGEMAN FUEL INJECTION PUMP Filed June 29. 1955 ATTO/P/VL'X INVENTOR. HA Ns HOG EMAN a a a w w United States Patent Oflice 2,797,644 Patented July 2, 1957 FUEL INJECTION PUMP Hans Hogeman, Longmeadow, Mass., assignor to American Bosch Arma- Corporation, a corporation of New York Application June 29, 1953, Serial No. 364,803

2 Claims. (Cl. 103-41) This invention relates to fuel injection pumps and the object of the invention is to provide a new and improved fuel injection pump wherein means is provided for dampening or restricting flow of fuel back into the pumping compartment and thereby preventing extreme pressure waves or fluctuations which can cause cavitation erosion of the pumping plunger and its barrel and can also protect or eliminate the need for baflie screws in the fuel sump and also improve uniformity of delivery by the pump by preventing spill back so violent as to cause non-uniformity in metering whereby a wave condition may affect the next delivery by the pump.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings wherein the preferred form of the invention has been given by way of illustration only.

Referring to the drawings:

Fig. 1 is a fragmentary sectional view of a fuel injection pump embodying the invention;

Fig. 2 is a fragmentary sectional view showing a form slightly modified from the form of Fig. 1; and

Fig. 3 is a fragmentary sectional view taken on line 3-3 of Fig. 1 looking in the direction of the arrows.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout, the device shown embodying the invention comprises the pump housing in which is positioned the barrel 11. having the ports 12 and 13 and in alignment therewith are provided the baflle screws 14 in the housing 10.

Within barrel 11 is the plunger 15 adapted to be reciprocated within the bore 16 in the barrel 11 to eifect pumping action of fuel or fluid which is then forced past delivery valve 17 in delivery valve housing which is raised from its seat by the force of the pump fluid against the action of delivery valve spring 18 and the pumped fluid then passes through outlet 19 land a delivery hue, not shown, to the proper engine cylinder.

Intermediate the pumping chamber or bore 16 and the delivery valve 17 is positioned a snubber valve arrangement. This snubber valve arrangement comprises the snubber valve body 21 having an opening 22 therethrough and having a suitable number of drilled flow pockets 23 formed therein.

The aperture 22 has the valve disc 24 overlying the flow pockets 23 as shown in Fig. 3 and disc 24 has the restricted orifice 25 therethrough and said valve disc 24 is adapted to be retained in the portion 23a of orifice 22 by means of the lower valve seat 26 which has the aperture 27 therethrough.

Because of the flow pockets 23, which may be of any suitable number, and which are deeper than the portion 23a of the aperture 22, on the delivery stroke the valve disc 24 is raised by fluid pressure from engagement with lower valve seat 26 and fluid passes around valve disc 24 through flow pockets 23 to the delivery valve and any pressure waves or fluctuations flowing back toward the pumping chamber 16 from the delivery line seats valve disc 24 upon lower valve seat 26 and allows any flow back into the pumping chamber 16 to come through orifice 25 therein which, because of its limited size, dampens or restricts the flow back into the pumping compartment and. prevents extreme pressure waves or fluctuations which can cause cavitation erosion of the pumping plunger 15 and its barrel and the walls of housing 10 in alignment with ports 12 and 13 which walls are ordinarily protected by means of baffle screws 14 which are also protected and possibly eliminated by the present invention.

It will also be seen that due to the present invention the spilling of fluid back into the pumping chamber which has been in some instances found so violent as to cause non-uniformity in metering is eliminated and thereby the uniformity of delivery improved.

In Fig. 2 there is shown a slightly modified form of the invention in that the aperture 22 and enlarged portion thereof 23a are formed directly in the delivery valve housing 20 and lower valve seat 26 is retained in a bore in the lower face of delivery valve housing 20 by means of spring retaining ring 28.

From the foregoing it will be seen that I have provided novel, simple and eflicient means for obtaining all of the objects and advantages of the invention.

I claim:

1. In a fuel injection pump, a pump body having a bore, a plunger mounted for reciprocation in said bore, a fuel inlet passage communicating with said bore for supplying fuel thereto and a fuel delivery passage in said pump body and communicating with said bore for delivering fuel pumped by said plunger, a delivery valve in said fuel delivery passage, said delivery valve comprising a seat, a valve member and resilient means normally urging said valve member toward engagement with said seat whereby the passage of fuel past said delivery valve is prevented except when said delivery valve is moved away from said seat by pressure of fuel from said pumping chamber and flow control means in the delivery passage in said pump body between said pumping chamber and said delivery valve, said flow control means comprising a valve member for allowing substantially unrestricted flow from said pumping chamber through said fuel delivery passage to said delivery valve, while restricting the fuel flow from the delivery valve back into the pumping chamber to prevent erosion of said plunger by said returning fuel and tending to eliminate the effects of said returning fuel upon the metering of the fuel in said pumping chamber.

2. In a fuel injection pump, a pump body having a bore, a plunger mounted for reciprocation in said bore, a fuel inlet passage communicating with said bore for supplying fuel thereto and a fuel delivery passage in said pump body and communicating with said bore for delivering fuel pumped by said plunger, a delivery valve in said fuel delivery passage, said delivery valve comprising a seat, a valve member and resilient means normally urging said valve member toward engagement with said seat whereby the passage of fuel past said delivery valve is prevented except when said delivery valve is moved away from said seat by pressure of fuel from said pumping chamber and flow control means in the delivery passage in said pump body between said pumping chamber and said delivery valve, said flow control means comprising a valve memberfo'r allowing substantially unrestricted flow from said pumping chamber through said fuel delivery passage to said delivery valve, While restricting the fuel flow from the delivery valve back into the pumping chamber to prevent erosion of said plunger by said returning fuel and tending to eliminate the effects of said returning fuel upon the metering of the fuel in said pumping chamber, said flow control means comprising a valve member having a restricted opening to restrict the flow of fuel back into the pumping chamber and passage means adjacent the periphery of said valve member to allow substantially unrestricted flow of fuel from said pumping chamber to said delivery valve through said fuel delivery passage in said pump body.

References Cited in the file of this patent UNITED STATES PATENTS Camner Aug. 24, 1937 Truxell Jan. 24, 1939 Camner Apr. 1, 1952 Nichols Ian. 3, 1956 FOREIGN PATENTS Switzerland Apr. 1, 1931 Italy Aug. 4, 1951 Great Britain July 2, 1937 

